Sunday, July 22, 2012

Cleantech News from CleanTechnica

A California scientist has developed a synthetic form of spider silk created by living bacteria, and in a life-imitates-art twist his research track is running parallel to the storyline of the fictional superhero Spider-Man. In both cases, the result has been a renewable, nontoxic biomaterial that relies on energy efficient natural processes for its fabrication, dovetailing neatly with President Obama’s recent call for a national bioeconomy blueprint that transitions the U.S. out of dependency on petrochemicals and energy-intensive manufacturing systems.

Spider-Man and Biobased Spider Silk: a Timeline

Scientists have long been trying to recreate the superpowers of spider silk, which is about five times stronger than steel but thin, flexible, and durable.

As with Mr. Parker, who originally formulated his spider silk in the lab, initial attempts focused on chemical processes that yielded new synthetic materials like Kevlar.

In the late 1990′s, Dr. Craig Vierra of the University of the Pacific began studying the protein structure in the silk of the black widow spider. By sheer coincidence (or was it?), Black Widow got her start with Spider-Man back in the 1970′s.

By the late 2000′s, Dr. Vierra’s research had become part of a trend toward producing artificial spider silk through a natural self-assembly process, using “expression systems” found in yeast and bacteria as well as goats.

In the meantime, Mr. Parker underwent a startling transformation. Perhaps concerned that real-life scientists were on track to create a true artificial spider silk, in 2004, Mr. Parker gained an expression system of his own, giving Spider-Man the truly unique ability to self-assemble biobased spider silk internally.

Spinning Artificial Spider Silk

Critical to the success of Mr. Parker’s new power was the growth of spinnerets in his forearms, which transform the amorphous pre-silk into a powerful thread as it exits his body. That is, coincidentally, the area in which Dr. Vierra’s latest research is focused. The properties of spider silk are known on a molecular level, and the next step is figuring out how to assemble those molecules into a strong thread.

Dr. Vierra seems to be on track to catch up to Mr. Parker. In 2010, he won a grant from the National Science Foundation for a four-year project called Molecular Characterization of Black Widow Spider Silk. The goal is to mimic the spider’s natural “post-spin” process, in which the molecules in the silk fiber are aligned to increase its tensile strength.

To accomplish that, Dr. Vierra and his team have developed a mechanical actuator that can stretch artificial spider silk with far more precision than previous methods allowed.

Research is also continuing apace on other biobased means of producing artificial spider silk, including a project to tweak real spider silk with zinc and other materials, and one to bioengineer silkworms into producing stronger silk.